Conventionally, coating and printing are generally applied on a surface of a metallic container such as food can which preserves foods etc and beverage can for imparting corrosion resistance and decoration.
For instance, JP-A-6-306325 discloses a resin composition for an aqueous coating material comprising an acrylic emulsion, an acrylic modified epoxy resin and an amino resin. However, the acrylic emulsion contains a monomer contributing to crosslinking, and water with high surface tension is used as a solvent. As the result of causing material contraction at heat treatment, pinholes occur in the coating film, thus, the acrylic emulsion is not fully satisfactory in terms of corrosion resistance and decoration.
Also, JP-A-2000-53892 describes a coating material containing polyethylene terephthalate (PET) resin powder. The PET resin powder is prepared by separating out particles by water cooling from a solution of mixed pellets containing a regenerated PET resin. However, a cooling speed of the solution of the mixed pellets is slow since water cooling is used as a means of cooling in this process, and an average particle size of the obtained particles is about 40 μm at minimum, which is significantly large. Therefore, a coating film comprising this coating material becomes thick, depending on the average particle size of the particles contained thereto, and the PET resin is not fully satisfactory in viewpoints of appearance, processability and cost.
JP-A-11-156998 describes a metal plate on which a film without pinholes is laminated. However, there is a limitation to thin down the laminate film, and it is difficult to obtain a thinner film with a thickness of about a few μm. Consequently, the metal plate is not fully satisfactory in viewpoints of appearance, processability and cost.
JP-A-2002-120278 describes a process for preparing a resin coated metal plate in which a film is prepared by heat-melting a thermoplastic resin and the obtained film is pressurized to adhere to a metal plate by a pressure roll and then cooled rapidly to at most Tg. However, the equipment is too grand and there is a limitation for making a thin film as well as JP-A-11-156998. Consequently, the resin coated metal plate is not fully satisfactory in viewpoints of appearance, processability and cost.